Clouds Are Liquid Water
In short, clouds are tiny droplets of water, so small that they float in the air. Here’s how they form: when water gets hot enough, (like when you boil it), it turns from a liquid into a gas. That gas, called water vapor, is invisible, and lighter than air, so it floats up just like a balloon. The higher you go, the colder it gets, so once that water vapor gets high enough, it's ready to turn back into liquid water.